while 1:
a=raw_input()
j=a[0]
for i in range(1,len(a)):
if a[i] < a[i-1]:
j=a[i]
if i+1 < len(a) and a[i+1] >= a[i-1]:
print j;break
elif i+1>=len(a):
print j;break
else:
print a[i-1];break
Note that non-ascii characters in the above source code will be escaped (such as \x9f).